Absorption tower



March 19, 1957 J. s. F. CARTER 2,785,961

ABSORPTION TOWER Filed May 5, 1953 3 Sheets-Sheet l Tel/11: 35.]? Curfew March 19, 1957 J. 5. F. CARTER ,78

. ABSORPTION TOWER Filed May 5, 1953 3 Sheets-Sheet 2 I NVE N TOR.

March 19, 1957 J. s. F. CARTER ABSORPTION TOWER 3 Sheets-Sheet 3 Filed May 5, 1953 owo o o w w 0 0 a o o 0 OO O O O O O O O O O o o w m o O O O O O OO1\ 1 O O IN! E N TOR.

A TTOR NE Y5- United States Patent o ABSORPTION TOWER James S. F. Carter, Oceanside, N. Y., asslgnor to Carter & Nansen Co., Inc., New York, N. Y., a corporation of New York Application May 5, 1953, Serial No. 353,154

6 Claims. (Cl. 23-283) The present invention relates to apparatus for contacting gas or vapors with liquid and particularly to that type of apparatus commonly known as absorption towersl More particularly still the invention relates to an absorption tower particularly adapted for the removal of ammonia from a mixture of gases by a counter-current operation in which the gases rise through water which flows downwardly from one tray to another of a series.-

Since the absorption of ammonia is an exothermic process and may be conducted under high pressure conditions, for example, at 100 pounds per square inch, the problem of heat removal becomes critical.

Many attempts have been made to solve this problem, but all have resulted in bulky and expensive equipment. Amongst the solutions suggested in the past was the placing of cooling pipes within the tower and resting upon the absorption trays so as to occupy space thereon which resulted in decreasing the absorption capacity and was therefore not a satisfactory solution.

Another proposed solution of the problem was to pump the liquid into cooling chambers located outside the tower proper at various levels of the tower. This, of course, involved the erection of the framework at the chosen levels and provision for separately housed external coolers and resulted in complicated and expensive packing, pumping and piping, increasing the normal expectation of leakage and repair. I

My present invention provides an absorption tower adapted to provide a large amount ofcooli-ng' surface but without decreasinghthe. absorption "surface'jjand without necessitating separately housed, external cooling chamb'ers" 1and;the concomitant expenselof erection and 'in'aintenancethereof.- 'j 1 I 'In;accordance" with 'the" present invention bfun {of horizontally extending "cooling tubes"areprovide'd, these tubes lying along chords of the cylindrical tower, a portion of the tubes lying therefore within the tower and the ends thereof lying outside the tower. In conjunction with the tube bundles weirs are provided so that the absorbing liquid flows downwardly from one tray to another passing over the bundle of cooling tubes as it descends, the cooling tubes at one level being at one side of the tower and at the next lower level at the opposite side, or in some instances cooling bundles may be provided at the ends of a bubble tray and at the center of the next lower bubble tray continuing alternately in this manner.

It is an object of the invention to providean absorption tower of the bubble tray type particularly adapted for use in exothermic processes and wherein the cooling means does not materially interfere with the area available for absorption.

It is another object of the invention to provide such an absorption tower which requires no external cooling chambers and therefore eliminates the expensive and difficult to maintain external chambers together with the piping, packing and other piping adjuncts necessary.

Other objects and features of the invention will be ap- "ice parent when the following description is considered in connection with the annexed drawings, in which,

Figure 1 is a broken vertical cross-sectional view of an absorpton tower in accordance with the present invention;

' Figure 2 is a horizontal cross-sectional view of the absorption tower of Figure 1 showing particularly the arrangement of one bundle of cooling tubes and the headers therefor together with the weirs for directing the flow over these tubes and the mode of supporting the tubes within their housing and within the absorption tower proper;

Figure 3 is an enlarged vertical cross-sectional view of the cooling tower at a single level showing the details of location of the cooling tube bundles and of certain weirs which are provided to maintain the liquid level onfthe' bubble trays at the desired height; and

Figure 4 is a vertical cross-sectional view similar to Figure 1 showing that modification of the invention wherein the cooling tube bundles are located at diametrically opposite points on the perimeter of one bubble tray and at the center of the succeeding lower bubble tray, the pattern being followed throughout the bubble tray arrangement so that the flow is that known as adouble cross-current flow.

Referring now to the drawings and particularly to Figure 1 thereof, gases which enter'thetowerthrough lower inlet 10 rise and are absorbed by. the water, the nonabsorbed portion being taken oli at 11. Water enters the upper inlet. 12 and flows onto the uppermost horizontal flat'tray 13 which tray is provided with risers therethrough and with bubble caps 14 of any usual type. The

liquid level is maintained on the tray 13 by means ofa weir 15 so as to ensure that the slots formed in the hub. ble caps 14 are submerged. From the uppermost tray 13 the liquid flows past serrations 19 in'the notched weir 15 over a deflecting plate 16 onto a bundle of pipes 17 the details of which will be described later.

The weir 15 extends downwardly and below the level.

ce nter j lirl eof the tube bundle and extending abov'e'thef level of the bottom of weir 15 which plate prevents a flow-of liquid over thedeflecting plate 16 down the side wall of the tower and across the tray without coming into contact with the: cooling tubes 17-: g' 5-;

"At each "tray level the arrangement" above-described is repeated, the cooling tube bundles, however, being located at opposite sides of the bubble trays. Thus the descending liquid passes over the uppermost tray, thence over the tube bundle at the left of that tray, back to the right over the next lower tray, over the next bundle of cooling tubes, etc. until it finally reaches the lowermost tray and is discharged over the lowermost bundle of cooling tubes and drawn off at the outlet 21.

The details of the arrangement of the tube bundles and cooperating parts are best seen in Figures 1 and 2. As shown in those figures plates 22, arcuate in shape, are welded to the external wall 23 of the cooling tower, these plates having cylindrical housings 24 fixed thereto thus forming cylinders intersecting the cylindrical tower wall 23. At either end of the housing 24 tube sheets 25 are provided and tubes 17 extend from one bonnet or header 29 to the other of the pair.

Cooling fluid is pumped into an inlet such as 26 and out through an outlet such as 2'7, the various inlets and outlets being arranged in any desired fashion. Although a parallel arrangement so that the cooling fluid passes through one set of tubes only, is preferred, the cooling linuidrmaypass through two or morse-sets' of tubes 17in series.

The tubes are s'upported'in a tube-supporting plate 28 which rests upon the next lower tray 13 and is held in: Position ,by thentie rods 30- which extendbetween prawns an one. bflthe iaibersheewas nee'r gnre s z metrically opposites points of alternate traysand een-' early of t'helin't'erveningtrays. Consequently, the "flow is'butwardly fronrthe uppermost tray, through the cooling' tube blundlesiat the periphery and thenceinwardly (wt-.1",- the lneiitilower tray to the centerthere'of; through a diariietiic'ally extending opening and thence T througha bundle of cooling tubes17 extending along Iadiarn eter efthe tray and parallel -to., the bundles atthe; peripheries of adjacent tray's and: outwardly ove'r'..'thislthird tray, the

patternPbeingarepeated until the vliquid is'lfin'ally .dis

While' I have described the preferred embodiment of my invention it- Willbe understoodrthat many-'othermodifieations. may'lbe made without deviating! from the .prindiples thereof. 'For example, the cooling tower proper might be rectangularin cross section and likewise the tiibelbun'dles and the'tube bundle housings might be rectangular,.rather"than circular .in cross section. I wish, therefore, to' be limited not by the foregoing description but on the contrary solely by thelclairns granted tome.

.Whatis claimed is:

*LIIn aeylindrical absorptioniower of the type havi'n'g a plurality of circular bubblettraysand requiring cooling for the absorbing liquid, theimprovement which comp'rises'terminating alternate trays along chords lying at opposite -ends .of'a diameter, dividing the intervening trays into'two' portions separated by a slot lying parallel to the terminating chords of the alternate trays, mounting. aliun'dle of cooling fluid tubes above the alternate trays atthe center thereof andbeneath the slotin the intervening traynext'above and mounting pairsbfbundies of, cooling 'fiuid tubesaboveveac'h intervening tray, each'said'pair ofbundles being beneath the space between theternsihating chord of an alternate tray and the wall of the absorption tower weirs adjacent theedges of-feach bubble tray .to maintain the fluid at a desired level, said tube' bundles mounted above the'intervening trays, having their ends extending exteriorly of the absorption tower and being mounted inihousingslfixed' to absorption tower .wherebyf liquid Y'fiows. outwardly over one inay downwardlytthrough said coolingsfluid bundles, inwardlynoverlther-next loweritray and "downwardly through the center cooling -fiuidatubecbundle. 2.:3111 a cylindrical-absorption tower :otv the type hav- -=ing-ea sphirality transverse eneral'ly "circular bubble trays, and requiring cooling of the absorbing liquid, the

improvement" which comprises terminating each' tray along a chord and leaving afspace between said tray and the cylindrical wall of the tower, alternate trays being thus spaced from the tower wall at opposite edges, a bundle of cooling fluid tubes located below said tray at the side adjacent the terminatim gibhord of said tray, said tube bundle beingaalsolocated.withinmthe space defined by the planes of a pair' of adjaeent'trays, a baflie wall connected tarherupper dfisaidpairldf traysra'nditerminat-l in grshort :ofi thetlower.ofisaiidfrtraysand extend-ing downwardly adjacent the bundle of cooling fiuidtubes'; avertically upstanding weir connected to-..the lower .of said pair of'trays and extending substantially as high as the top of the bundle fof -ceolingiitubesgstiid baffie extending generally parallel to said weir and between said Weir and the lower wall nearest the weir, the lower edge of said bafile extending substantially as low as the lowermost cooling tube in "said gbundle, adjacent traysihaving bfibblecaps'therein and overflow weirs along said terminatingrhdrds V s' '3. An abs'orpti'onttowerassclairned in claim 2,1characterizedin thareaehisaid'cooling fluid tube 'bundle extends-ina direction substantially p'a'r'allel'to the terminating'ichordjlof' the trays, the ends'of'thetubes in said bundie "extendingputsidethe walls of" the tower, said tube endsbeing'piaced'lin' housings fixed to the walls of the eooling towerproper.

"4. Adevice'as clairne'd in claim 2, characterized inthat said'tube bundlesand'theliousing's' therefor are generally yl i l A device as "claimed inclaim 2, characterized in that a deflection plate is provided I for "each tray; each said' deflectionplateextending across said weir,sa'id deflectionfplate liquidifrom'a tray over the bundle of "eoGIingQfiuid' tubesisupported' above the next lower tray.

'6.-A""device,as claimed 'inielaim'. 2, characterized in that a-- baffle "plate 'iextends' substantially longitudinally (if-each said tube bundle; said "bafile'platel being mounted on' sai'd tray randextending upwardly, said plates serving to prevent absorbing "liquid from flowing along the walls""of"the"'absorption tower "and out :onto a' lower tray without passingthronghs'aid bundle of cooling ffluid tubes.

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1. IN A CYLINDRICAL ABSORPTION TOWER OF THE TYPE HAVING A PLURALITY OF CIRCULAR BUBBLE TRAYS AND REQUIRING COOLING OF THE ABSORBING LIQUID, THE IMPROVEMENT WHICH COMPRISES TEMINATING ALTERNATE TRAYS ALONG CHORDS LYING AT OPPOSITE ENDS OF A DIAMETER, DIVIDING THE INTERVENING TRAYS INTO TWO PORTIONS SEPARATED BY A SLOT LYING PARALLEL TO THE TERMINATING CHORDS OF THE ALTERNATE TRAYS, MOUNTING A BUNDLE OF COOLING FLUID TUBES ABOVE THE ALTERNATE TRAYS AT THE CENTER THEREOF AND BENEATH THE SLOT IN THE INTERVENTING TRAY NEXT ABOVE AND MOUNTING PAIRS OF BUNDLES OF COOLING FLUID TUBES ABOVE EACH INTERVENING TRAY, EACH SAID PAIR OF BUNDLES BEING BENEATH THE SPACE BETWEEN THE TERMINATING CHORD OF AN ALTERNATE TRAY AND THE WALL OF THE ABSORPTION TOWER WEIRS ADJACENT THE EDGES OF EACH BUBBLE TRAY TO MAINTAIN THE FLUID AT A DESIRED LEVEL, SAID TUBE BUNDLES MOUNTED ABOVE THE INTERVENING TRAYS HAVING THEIR ENDS EXTENDING EXTERIORLY OF THE ABSORPTION TOWER AND BEING MOUNTED IN HOUSINGS FIXED TO SAID ABSORPTION TOWER WHEREBY LIQUID FLOWS OUTWARDLY OVER ONE TRAY DOWNWARDLY THROUGH SAID COOLING FLUID BUNDLES, INWARDLY OVER THE NEXT LOWER TRAY AND DOWNWARDLY THRAOUGH THE CENTER COOLING FLUID TUBE BUNDLE. 